Scientists believe the current heatwave may be contributing to the unusually large numbers of whales and dolphins off Scotland's east coast.

The sea around Aberdeenshire is proving to be a particular hot spot for marine mammals, with many more minke whales recorded than normal.

The whales, which grow to about 28ft, have been seen congregating inshore near Aberdeen and further north.

They have also been seen feeding close to the surface in the Moray Firth.

Other unusual sightings over the past week include: a fin whale at North Berwick; a whale, believed to be a pilot whale, at St Cyrus; six risso's dolphins off Girdleness near Aberdeen and large groups of white-beaked dolphins further offshore.

Groups of up to a dozen common dolphins have also been seen at Fraserburgh and a humpback whale in the Outer Hebrides.

Dr Peter Evans, director of the Sea Watch Foundation, a marine conservation charity and research organisation, said: "Harbour porpoises and bottlenose dolphins are more or less resident in the Moray Firth and off the Aberdeenshire coast, but common dolphins occur mainly around the south-west of Britain.

"And risso's dolphins are rare in the North Sea, although they have been seen a number of times in the last couple of years.

"The increase in sightings of these species in this area probably reflects the marked rise in sea surface temperatures which has taken place in recent years.

"We are still analysing figures, but we believe there are more sightings of both whales and dolphins in eastern Scotland this year compared to the same period last year."

He added that sightings of minkes off the west coast were particularly welcome as there was a decline in their numbers in the area last year due to a regional shortage of sprats on which they feed.

National Whale and Dolphin Watch takes place from 12-20 August around the coast of Britain.

The event is organised annually by the Sea Watch Foundation, to raise awareness of the 28 marine mammal species known to visit British and Irish waters.

Sightings are used by Sea Watch scientists to aid their research into the effects on whales and dolphins of factors such as global warming, marine pollution, and fishing.